Multi-body dynamics of a swimming frog: A co-simulation approach

A significant challenging task is to quantify the locomotor forces experienced by swimming animal because direct measurement of forces applied to the aquatic medium are not so feasible. It is advantageous to study the mechanics of animal locomotion for both engineers and biologists. An engineer can analyze motion and use in robotics field that approach also inform biologist to measure different parameters (e.g. muscle forces). Frogs are known as good swimmers and also webbed feet of frog help to swim efficiently in water. Living frogs propel in water by coordinated motion of their hindlimbs, achieving good propulsive efficiency and maneuverability. In this paper, a co-simulation technique to study the swimming locomotion of frogs is presented. Morphological data is collected from the living frog and used for developing the dynamic model. In this model, the body of the frog is modeled as ellipsoid and webbed feet are modeled as rigid flat trapezoidal plates to resemble the living frog. The dynamic behaviour of the swimming frog is simulated with multi-body dynamic co-simulation technique utilizing MSC ADAMS and Matlab/SIMULINK softwares. MSC ADAMS software is used to simulate the dynamics of the mechanical model whereas Matlab/SIMULINK is used to calculate the propulsive forces (drag force & added mass force) utilizing the kinematic information obtained from MSC ADAMS and mathematical models based on blade element theory. Different forces acting on the swimming frog are calculated and presented here.